The present invention relates generally to the field of treatments for male erectile impotence More specifically, it relates to a method and apparatus for treating impotence by controlling vascular blood flow through the penis.
Efforts to treat male erectile impotence have, in recent years, largely focused on implantable, inflatable prosthetic devices, such as those described in U.S. Pat. Nos. 4,596,242 and 4,572,16, both to Fischell. Typically, such prosthetic devices comprise an inflatable chamber surgically implanted within the penis, and a manual pump for controllably inflating the chamber with a biocompatible working fluid that is stored in a reservoir. Both the pump and the reservoir may also be surgically implanted, the pump being located in a portion of the anatomy (e.g., the scrotum) that permits convenient manual operation.
While such inflatable prostheses have achieved relatively widespread use, they do have some drawbacks. For example, the surgery required to implant these devices necessitates substantial and irreversible trauma to the internal tissues of the penis, leading to life-long dependency on the prosthesis. Similarly, repair and replacement of the prosthesis also require major surgery. The need to inflate the prosthesis necessitates a relatively large fluid reservoir that also must be surgically implanted, and which may cause discomfort to the user. The relatively large volume of working fluid often requires a considerable amount of pumping by the user to achieve erection, and the erection achieved may often be less than totally natural, in terms of size, rigidity, firmness, and angle.
While many patients have benefited from the inflatable implants described above, the limitations inherent in such devices have lead to the exploration for alternative therapies. Some success in this regard has been achieved for patients who suffer from certain types of vascular dysfunction in the venous system of the penis. Such patients experience venous incompetence, manifesting itself in abnormal venous drainage from the corpora cavernosa, the penile chambers that are normally distended with blood to achieve erection.
It has long been recognized that such venous incompetence can be treated by occluding one or more major penile veins, such as the deep dorsal vein. Venous occlusion is typically performed by ligation and/or balloon embolization. See, e.g., Lewis, "Venous Surgery for Impotence", Urologic Clinics of North America, Vol. 15, No. 1, Feb., 1988; Orvis et al., "New Therapy for Impotence", Urologic Clinics of North America, Vol. 14, No. 3, Aug., 1987; Trieber et al., "Venous Surgery in Erectile Dysfunction: A Critical Report on 116 Patients", Urology, Vol. 34, No. 1, July, 1989. Encouraging success rates have been achieved in suitable candidates for such surgery, with many patients being able to achieve substantially natural erections. Furthermore, the surgical procedures involved, while delicate, result in relatively little trauma to the penile tissue, leaving the tissue substantially intact except for the particular blood vessels involved in the surgery. Moreover, by leaving the corpora cavernosa and penile nerves virtually intact, the vascular occlusion technique is suitable for use in conjunction with pharmacological therapies.
With surgical vascular occlusion, however, relief is temporary in many cases, with collateralization of the penile veins being suspected as a principal cause of eventual failure. Such collateralization is considered to be a natural consequence of the permanent occlusion of a major venous path.
Consequently, there is a need for a treatment for impotence that provides all of the benefits of venous occlusion surgery, and yet which is less susceptible to long-term failure.